Infallibility in Traditions
The main reason for the infallibility of the Imams (`a) is the very mental reason, which was mentioned before. Furthermore, infallible Imams (`a) have considered infallibility as a brilliant characteristic of an Imam in their traditions. As an example, Imam Riza (`a) stated, “The Imam is away from faults and wrongdoing. He possesses especial knowledge and patience. He causes the organization of religion, the honor of Muslims, anger of the heterodox, and perishing of the infidel.”
Imam Riza (`a) also stated in the same tradition, “When the Exalted Allah selects a servant to manage others, He grants the selected servant an open chest for this duty, illuminates his heart with wisdom, and inspires the necessary sciences to him, so that he will be able to answer any question and tell the truth. This selected person will thus be away from sins or faults and supported by the Almighty. Allah has given him these qualifications to be as a reason for other servants. This is Allah’s blessing that grants everyone He wishes. And Allah possesses great blessings.”
Imam Sadiq (`a) described the Imam this way, “The Imam is a selected person from the Household of Prophet Muhammad (s), who is always observed and supported by Him. Allah guards him, saves him from Satan’s deceits, bad reputations, and calamities. He is away from all faults and wrongdoing.”
Amiral Mu’minin (`a) stated, “The greatest level of wilayat (guardianship) of the Imam –whose obedience is obligatory– is considering him as infallible from faults, slip, and intentional offense. He does not commit major (kabirah) or minor (saqhirah) sins, nor does he commit irreligious deeds or debauchery.”
 Usul Kafi, Vol 1, p. 200.
 Usul Kafi, Vol 1, p. 202.
 Usul Kafi, Vol 1, p. 204.
 Biharul Anwar, Vol 68, p. 389.